What is a critical value?

• A. A result that indicates a life-threatening condition requiring immediate clinician notification.
• B. Results within the reference range.
• C. Results used for calibration.
• D. Results used to calculate a dilution factor.

Answer: (A)

A critical value is a laboratory result that signals a life-threatening condition and requires immediate notification of the clinician so urgent patient management can occur. These values are not just outside the reference range; they fall into thresholds deemed dangerous enough to threaten the patient’s life, prompting rapid communication and action. Labs have specific protocols to verify the result, promptly inform the clinician, document that contact, and sometimes repeat the test to confirm.

For example, extremely high or low potassium, very high glucose, or severe acid–base abnormalities would be considered critical because they can cause rapid deterioration if not treated right away. In contrast, results within the reference range are considered normal and do not require urgent action. Calibration and dilution-factor calculations are not about patient danger signs; they are method-related processes.

So the best answer is: a result that indicates a life-threatening condition requiring immediate clinician notification.